Emerging technologies for optimizing recovery from heavy crude deposits

ABSTRACT

A method for extracting hydrocarbons from an underground reservoir that includes initiating a combustion reaction inside a reservoir by injecting oxidizing gas through a set of pipes arranged inside the injection well, thereby generating a combustion front, the path of which first meets an end of a horizontal portion of a production well and, subsequently, the other end of the same; and using an assembly of pipes located inside the production well to extract from inside the reservoir the hydrocarbons entering the horizontal portion.

The classic configuration of the state of the art for a process for recovery of hydrocarbons based in an in situ combustion process arranges of a vertical injector comprising an input and an output, said input being arranged at the top and superficial portion of well, and such output arranged in well's interior. Additionally, it arranges of a horizontal production well comprising a first vertical duct portion and a horizontal duct portion. The horizontal duct portion of the production well is substantially perpendicular to the vertical injector, and is oriented in a direction towards the injector well. The end of the production well closest to the injector well is called in the art as “toe” and the farther end to the injector well is called “heel”. The “heel” end of the horizontal zone is in direct connection with the vertical portion of the production well, which extends to the surface, outside the hydrocarbon reservoir. This technique is called “toe to heel,” which is an arrangement that geometrically defines an inverted “L” and is known in the art as THAI. Examples of the prior art are documents U.S. Pat. No 5,626,191, CA 2,255,071, CA 2,643,739, CA 2,579,854, CA 2,569,676, CA 2,246,461, U.S. Pat. No. 6,167,966, and the U.S. Pat. No. 5,211,230 publication that although prior to the THAI system as such, forward some of its essential elements.

The invention proposes, in the first place, the variant in the basic configuration, consisting in to reverse the orientation of the horizontal portion of the production well with respect to the vertical injector. Under this configuration, the horizontal portion of the production well is oriented in the same direction of the combustion front propagation, which defines an “L” in which the substantially horizontal portion is oriented in the opposite direction to the injector well. The proposed configuration supports its effectiveness in the way as is develops the combustion front which, in his path, improving the characteristics of crude and the petroleum mobility relations with respect to water and finally, better displacement of crude toward the production wells. Hence to make sure that the admission zone of recovered crude is located farthest from the ignition zone, precisely by the propagation effect of the combustion front, this would ensure a broad route of the displacement of crude in more optimal conditions of homogeneity and cooler relative temperatures. The invention proposes to extend the route of the combustion front by a change in the disposition of the horizontal or vertical production wells, without involving to sacrifice large areas of the reservoir, as usual with the technologies of the prior art.

Another object of the invention is to provide multiple derivations to a same horizontal production well, in order to enhance the crude recovery. These multiple admission derivations define the multilateralism of the well. Likewise the vertical injector could have multiple output derivations.

Another further object of the invention provides a multiwell arrangement where the horizontal portion of each horizontal production well be located radially and projected outward from the zone with respect to the vertical injector well, and therefore of the zone where it begins the combustion which is in harmony with the main objective of the invention above mentioned.

Another object of the present invention would be to install a series of control sensors in the surface and bottom of the well, in order to control the combustion front in real time and distance. The concept has been called Synchronization Operations.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a typical cross-sectional schematic view of a configuration of an injector well and horizontal production well according to the prior art.

FIG. 2 shows a cross-sectional schematic view of a configuration of an injector well and horizontal production well according to the invention.

FIG. 3 reveals a representation of an injector well and horizontal production well has multiple admission derivations.

FIG. 4 represents an injector well that has multiple output derivations and a single horizontal well according to the invention.

FIG. 5 shows an injector well which has multiple output derivations and a horizontal production well which has multiple admission derivations.

FIG. 6 reveals a scheme of the multi well configuration proposed by the present invention.

GENERAL DESCRIPTION OF THE INVENTION

The process of the invention comprises as a first step providing at least one injector well (1) through which injected the means for initiating and/or maintaining the combustion reaction within the reservoir (100). Said injector well (1) comprises an assembly of pipes necessary and adapted to fulfill their task of serving like injector well in the process of the invention.

The second step comprises providing at least one production well comprising a substantially horizontal portion (6) and which presents a set of pipes suitable for extracting the hydrocarbons entering the production well (2) via the substantially horizontal portion (6). Said substantially horizontal portion (6) comprises a first end (7), and a second end (8). The end (8) determines a change of direction in the orientation of the well to the vertical portion (5) thereof, while standing the horizontal portion (6) of the production well of the invention so that the end (8) is in a relative position closest to the injector well (1) that the end (7).

The next step of the process is to initiate the combustion reaction within the reservoir injecting oxidizing gas through the pipe set present inside the injector well (1).

The next step of the process is to remove the hydrocarbon that is entering the horizontal portion (6) from inside the reservoir, through the pipe assembly within the production well (2).

PREFERRED CONFIGURATION OF THE INVENTION

FIG. 1 shows a basic configuration present in the prior art. This figure shows a vertical injector well (1) comprising two ends. A first end (3) for oxidizing gas intake (9) and a second end (4) through which enters the oxidizing gas (9) into the reservoir (1)00. A horizontal production well (2) comprises a substantially horizontal portion (6). The substantially horizontal portion (6) comprises an end (7) commonly called “toe” and the other end (8) called “heel” and determines a direction change in the orientation of the well toward the vertical portion of the same (5). In the reservoir can be clearly distinguished three contiguous zones each other. The first zone A that is where the combustion is initiated (ignition zone) and located in proximity of the injector well, the next in a B zone where coke is formed, and finally the C zone which is a zone where is the hydrocarbon that is being displaced by the combustion front. Under this principle the hydrocarbon to be extracted is driven to enter in the horizontal portion (6), by gravity and differential pressure. The recovered crude leaves the reservoir through the horizontal production well (2) by the end of the vertical portion (5).

FIG. 2 shows a configuration for carrying out the process of the invention. Said process comprises as a first step providing at least one injector well (1) through which are injected the required means for initiating and/or maintaining the combustion reaction within the reservoir (100). Said injector well (1) comprises an assembly of pipes necessary and adapted to fulfill their task of serving like injector well in the process of the invention. The injector well (1) comprises a body and two ends. The first end (3) is where the injection starts within the reservoir of the required means for carrying out the combustion reaction. Among the means that can be injected to the reservoir (100) from the end (3) there is an oxidizing gas. Among the gases which serve as oxidizing agent is found: air, oxygen enriched air, oxygen, or other oxidizing agent suitable for combustion. Among other means that can be injected into the reservoir with the oxidizing gas through the injector well (1), either simultaneously or sequentially, are agents that assist in the combustion such as, carbon dioxide, hydrogen donor agents, steam, water, aqueous solutions containing chemical compounds and/or mixtures thereof. The injection of hydrogen donor agents is performed in cases where it is desired to do besides the extraction process, an improvement of the hydrocarbon directly into the reservoir, so as to increase the API degree thereof. The injection of agents that assist in the combustion takes place in cases that requires increasing speed of the combustion reaction at the points at which the oxygen flow is low. In case in which water is injected, steam or aqueous solutions containing chemical compounds, the same can be injected through the same injector well (1), or through a different injector well provided for this purpose. In the case of steam, it can be injected into the hydrocarbon reservoir together with the oxidizing gas before the injection thereof, or after to sweep the petroleum not displaced by the combustion front, depending on the characteristics of hydrocarbon, petrophysical properties of the rock, and the extension of the combustion operation.

The injector well (1) has a second lower end (4) which is located inside the reservoir (100) of hydrocarbon. At the lower end (4) is where usually the gases and/or liquid fluids leave that were injected into the reservoir. However, the injector well (1) can present, along the length or part of the submerged section in the reservoir (100), a plurality of openings through which gases and/or liquid fluids enter within the reservoir. The plurality of apertures may be in a relatively high position with respect to the lower end (4), or relatively low, very close to or around said lower end (4). It is also contemplated in the invention the possibility of having at least two pluralities of openings on the submerged section in the reservoir of the injector well (1), preferably, a relatively high plurality, close to the roof of the reservoir, and a relatively low plurality very close to said lower end (4). The choice of the position of the apertures is chosen according to the reservoir geological conditions, and can control the flow through them, during the process to optimize the combustion reaction conditions, and consequently, the yield of production of the reservoir (amount of hydrocarbon displaced). The apertures extend along the length of the submerged section in the reservoir of the injector well (1), can occupy 100% of the length thereof, preferably between 10% and 60% of the length, more preferably between 10% and 35% of the length.

FIG. 2 shows the presence of a horizontal production well (2). The process of the invention contemplates as a second step providing at least one production well comprising a substantially horizontal portion (6), and having a set of pipes suitable for extracting the hydrocarbons entering to the interior of said production well (2) through the substantially horizontal portion (6). Said substantially horizontal portion (6) comprises a first end (7), and a second end (8). The end (8) determines a direction change in the orientation of the well toward the vertical portion (5) thereof. In the FIG. (2) can be observed that, unlike prior art (FIG. 1), the horizontal portion (6) of the production well of the invention is positioned such that the end (8) is in a relative position closest to the injector well (1), that the end (7). Due to this configuration, the displaced hydrocarbon front in its path will meet first with the end (8). The horizontal portion (6) can have at least a plurality of openings which may extend along the length of the horizontal portion (6) preferably being in a position near the end (7). The plurality of openings may extend along the length of the horizontal portion (6) occupying 100% of the length thereof, preferably between 10% and 60% of the length, more preferably, between 10% and 35% length. The relative position of the horizontal portion (6) of the production well with respect of the end (4) of the injector well (1) can be relatively high, coplanar, or relatively low, depending on geological conditions of the reservoir and of the hydrocarbon characteristics to be extracted. The present invention contemplates that the horizontal portion (6) of the production well (2) be horizontal, preferably substantially horizontal, although optionally could be made available at an angle to the horizontal plane. Similarly, one production well (2) may comprise more than one horizontal portion (6), as described above, the same can be or not to the same relative height in the well. The present invention also contemplates that the injector well (1) have a horizontal or substantially horizontal portion. Similarly, the same injector well (1) may comprise more than one horizontal portion, as described above, the same can be or not at the same height relative of well. In the event that the injector well (1) have horizontal portions, the same would meet the fact that the end thereof would be said end (4), and the plurality of apertures could be expanded to occupy 100% of the length thereof, preferably between 10% and 60% of the length, more preferably, between 10% and 35% of the length.

The next step of the process is to initiate the combustion reaction within the reservoir injecting oxidizing gas through the pipe set present inside the injector well (1). The means of initiation of the combustion reaction can be varied, preferably the reaction is initiated by prior steam injection or heating by a natural gas or electricity heater. Self ignition of the mixture of gas and oxidant is created by an appropriate chemical. As reference, FIG. 2 shows a state of progress of the combustion front. Due to the particular configuration of the horizontal portion (6) of the production well of the invention, the combustion front, regardless of the manner in which it moves, will be found with the first end (8) of the horizontal portion (6) and subsequently, with the end (7) of said horizontal portion (6). Within the reservoir (100) are clearly distinguished three contiguous zones to each other, A zone that is where the combustion starts (ignition zone), B zone where coke is formed, and finally, C zone which is a zone where the hydrocarbon is being displaced and, finally, by gravity and/or differential pressure, will enter into the horizontal portion (6) through the plurality of apertures present in said horizontal portion (6).

The next step of the process is drawn from inside the reservoir, through the pipe assembly within the production well (2), the hydrocarbon that is entering the horizontal portion (6). Hydrocarbon extraction is performed by standard extraction techniques which are not shown in the figures to facilitate understanding of the essential aspects of the invention. Note that the first material difference between the invention and the prior art derives from the orientation of the production well (2) as the direction in which extends the horizontal portion (6), is the same in which propagating the combustion front, and oriented, preferably in the opposite direction to the injector well (1). This is contrary to whichever occurs in the prior art wherein the portion (6) (FIG. 1) which extends in the opposite direction to the direction in which spreads the combustion front and facing the injector well.

Looking at FIGS. 3, 4, and 5, one can see that alternatively, may be provided combinations of injection-production wells, which could have a vertical injector well (1) without derivations and a horizontal well (2) with derivations or multiple lateral projections (11) and (12) (FIG. 3). Another possible alternative in the context of the invention contemplates an injector well (1) with lateral derivations (13) and (14), combined with a horizontal well (2) without derivations (FIG. 4). Additionally, it provides for the use of an injector well (1) with multiple lateral derivations (13) and (14) with a horizontal production, well (2) which in turn is also provided with multiple laterals derivations (11) and (12) (FIG. 5). The derivations are not limited in some cases those suggested from the figures, may be greater in number and in different arrangement or relative height on the reservoir, derivations settings can be horizontal, sloped. The number and arrangement of the derivations is variable and dependent on the reservoir geology and the proper conditions of exploitation. Multilateralism, or in other words have multiple laterals derivations has as object improving the supply of oxidizing agent or enhance the uptake of displaced hydrocarbon, to have greater admission relative area in derivations provided to this end of the horizontal well. Regardless of the type and number of derivations that could be found on the injector well (1) and/or the horizontal production well (2), the process of the invention always will be carried out by observing the relevant difference with respect to the prior art: The orientation of the horizontal portion (6) of the production well (2) is in reverse or contrary sense to the injector well (1). In addition to what has been described so far regarding the injection (1) and production (2) well, it is contemplated, when present multilateralism described in this paragraph, that these wells will be, preferably, of short or medium length, so as to optimize media distribution injected into the reservoir, the hydrocarbon extraction and control of the combustion front.

Additionally, the invention contemplates an arrangement scheme of several wells as the one proposed from FIG. 6. This figure shows a general arrangement of multiple production wells (2) according to the technique described in any of the previous figures. The invention is susceptible to be performed under any arrangement of wells, linear, distributed around an injector well, or without array defined, may have certain number of wells and nozzles and which in practice will be conditioned by reservoir conditions.

The invention contemplates to provide multiple variable sensors arranged along the length of part of the horizontal portion (6) of the horizontal well production (2) to monitor and control the combustion front. Moreover, the present invention may contemplate to install a series of control sensors in both surface and bottom wells, in order to control the combustion front in real time and distance.

The invention was presented by description as reference, which has to be seen and understood by a person with broadly knowledge of the art and techniques related to the same. Likewise, the drawings are for reference representations for easy viewing of the principles and contributions to the art and in this way should be interpreted broadly and not restrictive. 

1. Process for the extraction of hydrocarbon from an underground reservoir comprising providing at least one injector well comprising an assembly of pipes adapted to inject the necessary means to initiating and/or maintaining the combustion reaction within the reservoir; providing at least one production well comprising a substantially horizontal portion, and having a set of pipes suitable for extracting the hydrocarbons entering in the interior of said production well through the substantially horizontal portion, wherein said substantially horizontal portion comprises a first end, and a second end, while standing the horizontal portion of the production well so that the end is in a relative position closest to the injector well that the end; initiate the combustion reaction within the reservoir injecting oxidizing gas through the pipe set present inside the injector well which generates a combustion front what in its path, will meet with the first end of the horizontal portion and, subsequently, with the end; extracting from inside of the reservoir, through the assembly of pipes inside the production well, the hydrocarbon that is entering to the horizontal portion.
 2. Process according to claim 1, wherein the injector well, has, along the length or part of the submerged section in the reservoir. a plurality of openings through which gases and/or fluids liquid enter into the reservoir.
 3. Process according to claim 1, wherein the injector well has at least 2 pluralities of openings on the submerged section in the reservoir.
 4. Process according to claim 3, where openings extending along submerged section in the reservoir of the injector well, can occupy 100% of the length thereof.
 5. Process according to claim 1, where between the means to initiating and/or maintaining the combustion reactions is found: air, oxygen enriched air, oxygen or other oxidizing agent suitable for combustion and/or mixtures thereof.
 6. Process according to claim 5, where among other means that can be injected into the reservoir with the oxidizing gas, either simultaneously or sequentially, are agents that assist in the combustion such as, carbon dioxide, hydrogen donor agents, steam, water, aqueous solutions containing chemical compounds and/or mixtures thereof.
 7. Process according to claim 1, where the horizontal portion can have at least a plurality of openings which may extend along the length of the horizontal portion.
 8. Process according to claim 5, where the plurality of openings may extend along the length of the horizontal portion occupy 100% of the length thereof.
 9. Process for the extraction of hydrocarbon from an underground reservoir comprising providing at least one injector well comprising an assembly of pipes adapted to inject the necessary means to initiating and/or maintaining the combustion reaction within the reservoir and comprising multiple laterals derivations; providing at least one production well comprising a substantially horizontal portion, and having a set of pipes suitable for extracting the hydrocarbons entering in the interior of said production well through the substantially horizontal portion, wherein said substantially horizontal portion comprises a first end, and a second end, while standing the horizontal portion of the production well so that the end is in a relative position closest to the injector well that the end wherein said production well comprises multiple laterals derivations; initiate the combustion reaction within the reservoir injecting oxidizing gas through the pipe set present inside the injector well which generates a combustion front what in its path, will meet with the first end of the horizontal portion and, subsequently, with the end; extracting from inside of the reservoir, through the assembly of pipes inside the production well, the hydrocarbon that is entering to the horizontal portion.
 10. Process according to claim 10, wherein the injector well has, along the length or part of the submerged section in the reservoir, a plurality of openings through which gases and/or means enter into the reservoir.
 11. Process according to claim 9, wherein the injector well has at least 2 pluralities of openings on the submerged section in the reservoir.
 12. Process according to claim 11, wherein the openings extend along the length of the submerged section in the reservoir of the injector well, can occupy 100% of the length thereof.
 13. Process according to claim 9, where among the means to initiating and/or maintaining combustion reactions is found: air, oxygen enriched air, oxygen or other oxidizing agent suitable for combustion and/or mixtures thereof.
 14. Process according to claim 13, where among other means that can be injected into the reservoir with the oxidizing gas, either simultaneously or sequentially, are found agents that assist in the combustion such as, carbon dioxide, hydrogen donor agents, steam, water, aqueous solutions containing chemical compounds and/or mixtures thereof.
 15. Process according to claim 9, where the horizontal portion can have at least a plurality of openings which may extend along the length of the horizontal portion.
 16. Process according to claim 15, wherein the plurality of openings may extend along the length of the horizontal portion occupy 100% of the length thereof.
 17. Process according to claim 1, where contemplates the use of multiple variable sensors arranged along the length in part of the horizontal portion of the horizontal production well to monitor and control the front combustion.
 18. Process according to claim 1, where contemplates to install a series of control sensors both surface and bottom of wells, in order to control the combustion front in real time and distance. 